blk-rq-qos: refactor out common elements of blk-wbt
blkcg-qos is going to do essentially what wbt does, only on a cgroup
basis. Break out the common code that will be shared between blkcg-qos
and wbt into blk-rq-qos.* so they can both utilize the same
infrastructure.
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-wbt.c b/block/blk-wbt.c
index 4f89b28..6fe20fb 100644
--- a/block/blk-wbt.c
+++ b/block/blk-wbt.c
@@ -25,6 +25,7 @@
#include <linux/swap.h>
#include "blk-wbt.h"
+#include "blk-rq-qos.h"
#define CREATE_TRACE_POINTS
#include <trace/events/wbt.h>
@@ -78,28 +79,6 @@ static inline bool rwb_enabled(struct rq_wb *rwb)
return rwb && rwb->wb_normal != 0;
}
-/*
- * Increment 'v', if 'v' is below 'below'. Returns true if we succeeded,
- * false if 'v' + 1 would be bigger than 'below'.
- */
-static bool atomic_inc_below(atomic_t *v, int below)
-{
- int cur = atomic_read(v);
-
- for (;;) {
- int old;
-
- if (cur >= below)
- return false;
- old = atomic_cmpxchg(v, cur, cur + 1);
- if (old == cur)
- break;
- cur = old;
- }
-
- return true;
-}
-
static void wb_timestamp(struct rq_wb *rwb, unsigned long *var)
{
if (rwb_enabled(rwb)) {
@@ -116,7 +95,7 @@ static void wb_timestamp(struct rq_wb *rwb, unsigned long *var)
*/
static bool wb_recent_wait(struct rq_wb *rwb)
{
- struct bdi_writeback *wb = &rwb->queue->backing_dev_info->wb;
+ struct bdi_writeback *wb = &rwb->rqos.q->backing_dev_info->wb;
return time_before(jiffies, wb->dirty_sleep + HZ);
}
@@ -144,8 +123,9 @@ static void rwb_wake_all(struct rq_wb *rwb)
}
}
-void __wbt_done(struct rq_wb *rwb, enum wbt_flags wb_acct)
+static void __wbt_done(struct rq_qos *rqos, enum wbt_flags wb_acct)
{
+ struct rq_wb *rwb = RQWB(rqos);
struct rq_wait *rqw;
int inflight, limit;
@@ -194,10 +174,9 @@ void __wbt_done(struct rq_wb *rwb, enum wbt_flags wb_acct)
* Called on completion of a request. Note that it's also called when
* a request is merged, when the request gets freed.
*/
-void wbt_done(struct rq_wb *rwb, struct request *rq)
+static void wbt_done(struct rq_qos *rqos, struct request *rq)
{
- if (!rwb)
- return;
+ struct rq_wb *rwb = RQWB(rqos);
if (!wbt_is_tracked(rq)) {
if (rwb->sync_cookie == rq) {
@@ -209,72 +188,11 @@ void wbt_done(struct rq_wb *rwb, struct request *rq)
wb_timestamp(rwb, &rwb->last_comp);
} else {
WARN_ON_ONCE(rq == rwb->sync_cookie);
- __wbt_done(rwb, wbt_flags(rq));
+ __wbt_done(rqos, wbt_flags(rq));
}
wbt_clear_state(rq);
}
-/*
- * Return true, if we can't increase the depth further by scaling
- */
-static bool calc_wb_limits(struct rq_wb *rwb)
-{
- unsigned int depth;
- bool ret = false;
-
- if (!rwb->min_lat_nsec) {
- rwb->wb_max = rwb->wb_normal = rwb->wb_background = 0;
- return false;
- }
-
- /*
- * For QD=1 devices, this is a special case. It's important for those
- * to have one request ready when one completes, so force a depth of
- * 2 for those devices. On the backend, it'll be a depth of 1 anyway,
- * since the device can't have more than that in flight. If we're
- * scaling down, then keep a setting of 1/1/1.
- */
- if (rwb->queue_depth == 1) {
- if (rwb->scale_step > 0)
- rwb->wb_max = rwb->wb_normal = 1;
- else {
- rwb->wb_max = rwb->wb_normal = 2;
- ret = true;
- }
- rwb->wb_background = 1;
- } else {
- /*
- * scale_step == 0 is our default state. If we have suffered
- * latency spikes, step will be > 0, and we shrink the
- * allowed write depths. If step is < 0, we're only doing
- * writes, and we allow a temporarily higher depth to
- * increase performance.
- */
- depth = min_t(unsigned int, RWB_DEF_DEPTH, rwb->queue_depth);
- if (rwb->scale_step > 0)
- depth = 1 + ((depth - 1) >> min(31, rwb->scale_step));
- else if (rwb->scale_step < 0) {
- unsigned int maxd = 3 * rwb->queue_depth / 4;
-
- depth = 1 + ((depth - 1) << -rwb->scale_step);
- if (depth > maxd) {
- depth = maxd;
- ret = true;
- }
- }
-
- /*
- * Set our max/normal/bg queue depths based on how far
- * we have scaled down (->scale_step).
- */
- rwb->wb_max = depth;
- rwb->wb_normal = (rwb->wb_max + 1) / 2;
- rwb->wb_background = (rwb->wb_max + 3) / 4;
- }
-
- return ret;
-}
-
static inline bool stat_sample_valid(struct blk_rq_stat *stat)
{
/*
@@ -307,7 +225,8 @@ enum {
static int latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
{
- struct backing_dev_info *bdi = rwb->queue->backing_dev_info;
+ struct backing_dev_info *bdi = rwb->rqos.q->backing_dev_info;
+ struct rq_depth *rqd = &rwb->rq_depth;
u64 thislat;
/*
@@ -351,7 +270,7 @@ static int latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
return LAT_EXCEEDED;
}
- if (rwb->scale_step)
+ if (rqd->scale_step)
trace_wbt_stat(bdi, stat);
return LAT_OK;
@@ -359,58 +278,48 @@ static int latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
static void rwb_trace_step(struct rq_wb *rwb, const char *msg)
{
- struct backing_dev_info *bdi = rwb->queue->backing_dev_info;
+ struct backing_dev_info *bdi = rwb->rqos.q->backing_dev_info;
+ struct rq_depth *rqd = &rwb->rq_depth;
- trace_wbt_step(bdi, msg, rwb->scale_step, rwb->cur_win_nsec,
- rwb->wb_background, rwb->wb_normal, rwb->wb_max);
+ trace_wbt_step(bdi, msg, rqd->scale_step, rwb->cur_win_nsec,
+ rwb->wb_background, rwb->wb_normal, rqd->max_depth);
+}
+
+static void calc_wb_limits(struct rq_wb *rwb)
+{
+ if (rwb->min_lat_nsec == 0) {
+ rwb->wb_normal = rwb->wb_background = 0;
+ } else if (rwb->rq_depth.max_depth <= 2) {
+ rwb->wb_normal = rwb->rq_depth.max_depth;
+ rwb->wb_background = 1;
+ } else {
+ rwb->wb_normal = (rwb->rq_depth.max_depth + 1) / 2;
+ rwb->wb_background = (rwb->rq_depth.max_depth + 3) / 4;
+ }
}
static void scale_up(struct rq_wb *rwb)
{
- /*
- * Hit max in previous round, stop here
- */
- if (rwb->scaled_max)
- return;
-
- rwb->scale_step--;
+ rq_depth_scale_up(&rwb->rq_depth);
+ calc_wb_limits(rwb);
rwb->unknown_cnt = 0;
-
- rwb->scaled_max = calc_wb_limits(rwb);
-
- rwb_wake_all(rwb);
-
- rwb_trace_step(rwb, "step up");
+ rwb_trace_step(rwb, "scale up");
}
-/*
- * Scale rwb down. If 'hard_throttle' is set, do it quicker, since we
- * had a latency violation.
- */
static void scale_down(struct rq_wb *rwb, bool hard_throttle)
{
- /*
- * Stop scaling down when we've hit the limit. This also prevents
- * ->scale_step from going to crazy values, if the device can't
- * keep up.
- */
- if (rwb->wb_max == 1)
- return;
-
- if (rwb->scale_step < 0 && hard_throttle)
- rwb->scale_step = 0;
- else
- rwb->scale_step++;
-
- rwb->scaled_max = false;
- rwb->unknown_cnt = 0;
+ rq_depth_scale_down(&rwb->rq_depth, hard_throttle);
calc_wb_limits(rwb);
- rwb_trace_step(rwb, "step down");
+ rwb->unknown_cnt = 0;
+ rwb_wake_all(rwb);
+ rwb_trace_step(rwb, "scale down");
}
static void rwb_arm_timer(struct rq_wb *rwb)
{
- if (rwb->scale_step > 0) {
+ struct rq_depth *rqd = &rwb->rq_depth;
+
+ if (rqd->scale_step > 0) {
/*
* We should speed this up, using some variant of a fast
* integer inverse square root calculation. Since we only do
@@ -418,7 +327,7 @@ static void rwb_arm_timer(struct rq_wb *rwb)
* though.
*/
rwb->cur_win_nsec = div_u64(rwb->win_nsec << 4,
- int_sqrt((rwb->scale_step + 1) << 8));
+ int_sqrt((rqd->scale_step + 1) << 8));
} else {
/*
* For step < 0, we don't want to increase/decrease the
@@ -433,12 +342,13 @@ static void rwb_arm_timer(struct rq_wb *rwb)
static void wb_timer_fn(struct blk_stat_callback *cb)
{
struct rq_wb *rwb = cb->data;
+ struct rq_depth *rqd = &rwb->rq_depth;
unsigned int inflight = wbt_inflight(rwb);
int status;
status = latency_exceeded(rwb, cb->stat);
- trace_wbt_timer(rwb->queue->backing_dev_info, status, rwb->scale_step,
+ trace_wbt_timer(rwb->rqos.q->backing_dev_info, status, rqd->scale_step,
inflight);
/*
@@ -469,9 +379,9 @@ static void wb_timer_fn(struct blk_stat_callback *cb)
* currently don't have a valid read/write sample. For that
* case, slowly return to center state (step == 0).
*/
- if (rwb->scale_step > 0)
+ if (rqd->scale_step > 0)
scale_up(rwb);
- else if (rwb->scale_step < 0)
+ else if (rqd->scale_step < 0)
scale_down(rwb, false);
break;
default:
@@ -481,19 +391,50 @@ static void wb_timer_fn(struct blk_stat_callback *cb)
/*
* Re-arm timer, if we have IO in flight
*/
- if (rwb->scale_step || inflight)
+ if (rqd->scale_step || inflight)
rwb_arm_timer(rwb);
}
-void wbt_update_limits(struct rq_wb *rwb)
+static void __wbt_update_limits(struct rq_wb *rwb)
{
- rwb->scale_step = 0;
- rwb->scaled_max = false;
+ struct rq_depth *rqd = &rwb->rq_depth;
+
+ rqd->scale_step = 0;
+ rqd->scaled_max = false;
+
+ rq_depth_calc_max_depth(rqd);
calc_wb_limits(rwb);
rwb_wake_all(rwb);
}
+void wbt_update_limits(struct request_queue *q)
+{
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ if (!rqos)
+ return;
+ __wbt_update_limits(RQWB(rqos));
+}
+
+u64 wbt_get_min_lat(struct request_queue *q)
+{
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ if (!rqos)
+ return 0;
+ return RQWB(rqos)->min_lat_nsec;
+}
+
+void wbt_set_min_lat(struct request_queue *q, u64 val)
+{
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ if (!rqos)
+ return;
+ RQWB(rqos)->min_lat_nsec = val;
+ RQWB(rqos)->enable_state = WBT_STATE_ON_MANUAL;
+ __wbt_update_limits(RQWB(rqos));
+}
+
+
static bool close_io(struct rq_wb *rwb)
{
const unsigned long now = jiffies;
@@ -520,7 +461,7 @@ static inline unsigned int get_limit(struct rq_wb *rwb, unsigned long rw)
* IO for a bit.
*/
if ((rw & REQ_HIPRIO) || wb_recent_wait(rwb) || current_is_kswapd())
- limit = rwb->wb_max;
+ limit = rwb->rq_depth.max_depth;
else if ((rw & REQ_BACKGROUND) || close_io(rwb)) {
/*
* If less than 100ms since we completed unrelated IO,
@@ -554,7 +495,7 @@ static inline bool may_queue(struct rq_wb *rwb, struct rq_wait *rqw,
rqw->wait.head.next != &wait->entry)
return false;
- return atomic_inc_below(&rqw->inflight, get_limit(rwb, rw));
+ return rq_wait_inc_below(rqw, get_limit(rwb, rw));
}
/*
@@ -614,8 +555,10 @@ static inline bool wbt_should_throttle(struct rq_wb *rwb, struct bio *bio)
* in an irq held spinlock, if it holds one when calling this function.
* If we do sleep, we'll release and re-grab it.
*/
-enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio, spinlock_t *lock)
+static enum wbt_flags wbt_wait(struct rq_qos *rqos, struct bio *bio,
+ spinlock_t *lock)
{
+ struct rq_wb *rwb = RQWB(rqos);
enum wbt_flags ret = 0;
if (!rwb_enabled(rwb))
@@ -643,8 +586,10 @@ enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio, spinlock_t *lock)
return ret | WBT_TRACKED;
}
-void wbt_issue(struct rq_wb *rwb, struct request *rq)
+void wbt_issue(struct rq_qos *rqos, struct request *rq)
{
+ struct rq_wb *rwb = RQWB(rqos);
+
if (!rwb_enabled(rwb))
return;
@@ -661,8 +606,9 @@ void wbt_issue(struct rq_wb *rwb, struct request *rq)
}
}
-void wbt_requeue(struct rq_wb *rwb, struct request *rq)
+void wbt_requeue(struct rq_qos *rqos, struct request *rq)
{
+ struct rq_wb *rwb = RQWB(rqos);
if (!rwb_enabled(rwb))
return;
if (rq == rwb->sync_cookie) {
@@ -671,39 +617,30 @@ void wbt_requeue(struct rq_wb *rwb, struct request *rq)
}
}
-void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth)
+void wbt_set_queue_depth(struct request_queue *q, unsigned int depth)
{
- if (rwb) {
- rwb->queue_depth = depth;
- wbt_update_limits(rwb);
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ if (rqos) {
+ RQWB(rqos)->rq_depth.queue_depth = depth;
+ __wbt_update_limits(RQWB(rqos));
}
}
-void wbt_set_write_cache(struct rq_wb *rwb, bool write_cache_on)
+void wbt_set_write_cache(struct request_queue *q, bool write_cache_on)
{
- if (rwb)
- rwb->wc = write_cache_on;
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ if (rqos)
+ RQWB(rqos)->wc = write_cache_on;
}
/*
- * Disable wbt, if enabled by default.
- */
-void wbt_disable_default(struct request_queue *q)
-{
- struct rq_wb *rwb = q->rq_wb;
-
- if (rwb && rwb->enable_state == WBT_STATE_ON_DEFAULT)
- wbt_exit(q);
-}
-EXPORT_SYMBOL_GPL(wbt_disable_default);
-
-/*
* Enable wbt if defaults are configured that way
*/
void wbt_enable_default(struct request_queue *q)
{
+ struct rq_qos *rqos = wbt_rq_qos(q);
/* Throttling already enabled? */
- if (q->rq_wb)
+ if (rqos)
return;
/* Queue not registered? Maybe shutting down... */
@@ -741,6 +678,41 @@ static int wbt_data_dir(const struct request *rq)
return -1;
}
+static void wbt_exit(struct rq_qos *rqos)
+{
+ struct rq_wb *rwb = RQWB(rqos);
+ struct request_queue *q = rqos->q;
+
+ blk_stat_remove_callback(q, rwb->cb);
+ blk_stat_free_callback(rwb->cb);
+ kfree(rwb);
+}
+
+/*
+ * Disable wbt, if enabled by default.
+ */
+void wbt_disable_default(struct request_queue *q)
+{
+ struct rq_qos *rqos = wbt_rq_qos(q);
+ struct rq_wb *rwb;
+ if (!rqos)
+ return;
+ rwb = RQWB(rqos);
+ if (rwb->enable_state == WBT_STATE_ON_DEFAULT)
+ rwb->wb_normal = 0;
+}
+EXPORT_SYMBOL_GPL(wbt_disable_default);
+
+
+static struct rq_qos_ops wbt_rqos_ops = {
+ .throttle = wbt_wait,
+ .issue = wbt_issue,
+ .requeue = wbt_requeue,
+ .done = wbt_done,
+ .cleanup = __wbt_done,
+ .exit = wbt_exit,
+};
+
int wbt_init(struct request_queue *q)
{
struct rq_wb *rwb;
@@ -756,39 +728,29 @@ int wbt_init(struct request_queue *q)
return -ENOMEM;
}
- for (i = 0; i < WBT_NUM_RWQ; i++) {
- atomic_set(&rwb->rq_wait[i].inflight, 0);
- init_waitqueue_head(&rwb->rq_wait[i].wait);
- }
+ for (i = 0; i < WBT_NUM_RWQ; i++)
+ rq_wait_init(&rwb->rq_wait[i]);
+ rwb->rqos.id = RQ_QOS_WBT;
+ rwb->rqos.ops = &wbt_rqos_ops;
+ rwb->rqos.q = q;
rwb->last_comp = rwb->last_issue = jiffies;
- rwb->queue = q;
rwb->win_nsec = RWB_WINDOW_NSEC;
rwb->enable_state = WBT_STATE_ON_DEFAULT;
- wbt_update_limits(rwb);
+ rwb->wc = 1;
+ rwb->rq_depth.default_depth = RWB_DEF_DEPTH;
+ __wbt_update_limits(rwb);
/*
* Assign rwb and add the stats callback.
*/
- q->rq_wb = rwb;
+ rq_qos_add(q, &rwb->rqos);
blk_stat_add_callback(q, rwb->cb);
rwb->min_lat_nsec = wbt_default_latency_nsec(q);
- wbt_set_queue_depth(rwb, blk_queue_depth(q));
- wbt_set_write_cache(rwb, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
+ wbt_set_queue_depth(q, blk_queue_depth(q));
+ wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
return 0;
}
-
-void wbt_exit(struct request_queue *q)
-{
- struct rq_wb *rwb = q->rq_wb;
-
- if (rwb) {
- blk_stat_remove_callback(q, rwb->cb);
- blk_stat_free_callback(rwb->cb);
- q->rq_wb = NULL;
- kfree(rwb);
- }
-}
